It is well known that the manufacture of photographic products must be carried out in rooms with very low light. It often happens that the manufacturing and finishing operations for light sensitive photographic products take place in dark rooms in which the lighting is mesopic lighting. This is due to the fact that the light sensitive products are fogged with lighting that can be very low.
Safety regulations require employers to indicate the emergency exits to their personnel using permanent panels. In premises with mesopic lighting, it is necessary to illuminate such panels so that they can be seen.
U.S. Pat. No. 5,365,411 titled "Exit Signs With LED Illumination," Nov. 15, 1994, by Rycroft et al., and U.S. Pat. No. 5,105,568 titled "Illuminated Sign Having Stencil Panel And Reflector Panel," Apr. 21, 1992, by Branning describe signaling panels comprising a box surrounding a light source and a screen bearing the information to be displayed and having light transparent zones and arranged in front of the source so that the luminous information can be seen by an observer. In U.S. Pat. No. 5,105,568 the sources are arranged to surround the transparent zones. In U.S. Pat. No. 5,365,411 the sources are arranged on the edges of the box and the light is reflected and diffused to illuminate the information panel uniformly.
It is an object of the invention to produce a signaling device that can be used in a room with mesopic lighting to limit to the minimum the interference light caused by the presence of the device in the room.
It is another object of the invention to enable the utilization of the same device when the room is exceptionally illuminated with photopic light.